Semiconductor device with a bipolar transistor and method of manufacturing such a device

Abstract

The invention relates to a semiconductor device with a substrate and a semiconductor body of silicon comprising a bipolar transistor with an emitter region, a base region and a collector region which are respectively of the N-type conductivity, the P-type conductivity and the N-type conductivity by the provision of suitable doping atoms, wherein the base region comprises a mixed crystal of silicon and germanium, the base region is separated from the emitter region by an intermediate region of silicon having a doping concentration which is lower than the doping concentration of the emitter region and with a thickness smaller than the thickness of the emitter region, and the emitter region comprises a sub-region comprising a mixed crystal of silicon and germanium which is positioned at the side of emitter region remote from the intermediate region.

1. Semiconductor device with a substrate and a semiconductor body of silicon comprising a bipolar transistor with an emitter region, a base region and a collector region which are respectively of the n-type conductivity, the p-type conductivity and the n-type conductivity by the provision of suitable doping atoms, wherein the base region comprises a mixed crystal of silicon and germanium, the base region is separated from the emitter region by an intermediate region of silicon having a doping concentration which is lower than the doping concentration of the emitter region and with a thickness smaller than the thickness of the emitter region and the emitter region comprises a sub-region comprising a mixed crystal of silicon and germanium which is positioned at the side of emitter region remote from the intermediate region, characterized in that the sub-region comprising the mixed crystal of silicon and germanium extend substantially through the whole emitter region up to the interface with the intermediate region and the doping atoms of the emitter region are arsenic atoms. 
     
     
       2. Semiconductor device according to  claim 1 , characterized in that the germanium content of the emitter region is between about 20 and 100 at. %. 
     
     
       3. Semiconductor device according to  claim 2 , characterized in that the germanium content of the emitter region is about 40 at. %. 
     
     
       4. Semiconductor device according to  claim 1 , characterized in that the arsenic atoms are provided in the emitter regions by an ion implantation. 
     
     
       5. Semiconductor device according to  claim 4 , characterized in that the energy of the ion implantation is chosen such that the arsenic ions as implanted are positioned in the emitter region remote from the intermediate region. 
     
     
       6. Semiconductor device as claimed in  claim 1 , characterized in that the base region is doped with boron atoms and provided with carbon atoms with a concentration that is at least comparable with the concentration of the boron atoms. 
     
     
       7. Semiconductor device as claimed in  claim 1 , characterized in that the emitter region is contacted by a metal silicide formed of a sacrificial silicon layer on top of the emitter region. 
     
     
       8. A method of manufacturing a semiconductor device with a substrate and a semiconductor body of silicon comprising a bipolar transistor with an emitter region, a base region and a collector region which are respectively of the n-type conductivity, the p-type conductivity type and the n-type conductivity by the provision of suitable doping atoms, wherein the base region is provided with a mixed crystal of silicon and germanium, the base region is separated from the emitter region by an intermediate region of silicon having a doping concentration which is lower than the doping concentration of the emitter region and with a thickness smaller than the thickness of the emitter region and the emitter region is provided with a sub-region comprising a mixed crystal of silicon and germanium which is positioned at the side of emitter region remote from the intermediate region, characterized in that the sub-region comprising the mixed crystal of silicon and germanium is extended substantially through the whole emitter region up to the interface with the intermediate region and for the doping atoms of the emitter region arsenic atoms are chosen. 
     
     
       9. Method according to  claim 8 , characterized in that the germanium content of the emitter region is chosen between about 20 and 100 at. %. 
     
     
       10. Method according to  claim 8 , characterized in that the arsenic atoms are provided in the emitter region by ion implantation. 
     
     
       11. Method according to  claim 10 , characterized that the energy of the ion implantation is chosen such that the arsenic atoms as implanted are positioned in the emitter region remote from the intermediate region. 
     
     
       12. Method according to  claim 8 , characterized in that a thin sacrificial silicon region is grown on top of the emitter region which is converted with a metal to a metal silicide contact region.